1. Field of the Invention
The present invention relates to a process for converting cellulose in hydrated molten salts.
2. Description of the Related Art
U.S. Pat. No. 1,943,176 to Graenacher discloses a process for dissolving cellulose in N-ethylpyridinium in the presence of nitrogen-containing bases.
Zhu et al., Green Chem., 2006, 8, 325-327 discloses dissolution of cellulose in a number of ionic liquids, in particular 1-butyl-3-methylimidazolium chloride (BMIMCI) and 1-allyl-3-methylimidazolium chloride (AMIMCI). Microwave heating accelerates the dissolution process. Cellulose can be regenerated from the ionic liquid by addition of water, ethanol, or acetone. The authors suggest the use of ionic liquids for the fractionation of lignocellulosic materials and the preparation of cellulose derivatives and composites.
Swalotski et al. report on the use of ionic liquids, such as BMIMCI, for the preparation of cellulose fibers. See U.S. Pat. No. 6,824,599 B2
U.S. Pat. No. 4,999,149 to Chen discloses a process for high strength cellulose fiber. Dissolving grade cellulose (i.e., cellulose that is substantially lignin free) is dissolved in ZnCl2 at elevated temperature. The cellulose/zinc chloride mixture is extruded into a coagulation medium.
The prior art processes use expensive materials for the ionic liquids. In addition, the disclosed processes do not convert cellulose other than from one form of cellulose to another form of cellulose.
The present invention provides a process for dissolving low-grade cellulose in inexpensive ionic liquids. The present invention further provides a process for purifying cellulose, and a method for converting cellulose, in particular to cellulose fibers.